Radiation Oncology/Physics/Photophysics

• Basic photophysics in the framework of photobiology is concerned with processes that occur when sunlight, filtered through the Earth's atmosphere, interacts with matter (atoms and molecules) present on Earth
• The spectrum of solar radiation striking the Earth spans 100 nm to 10⁶ nanometers (1 nm = 10^-9 m) and can be divided into the ultraviolet (UV) range (100 nm to 400 nm), visible range (400 nm to 700 nm) and infrared (IR) range (700 nm to 10⁶ nm)
• UV radiation has both damaging and beneficial effects on living matter
  • UV radiation is also responsible for the photochemical reaction leading to production of the protective ozone layer in the atmosphere
• As the name suggests the visible part of the spectrum is the light that human eyes can detect
  • Visible light is only one small part of the electromagnetic spectrum, which is classified by wavelength into radio wave, microwave, infrared, visible, ultraviolet, X-rays and gamma rays